Increasingly, consumers are demanding portable devices, such as personal digital assistants (PDA's), MP3 players, portable memory systems, advanced cell phone systems and cameras. Traditional non-volatile memory storage systems, such as floppy disks, hard drives, and optical drives, are generally unsuitable for use in portable devices because they suffer from mechanical failures, excess weight, large size and high energy consumption. As a result, manufacturers of portable devices are turning to solid-state memory systems, such as flash memory and electrically erasable programmable read-only memory (EEPROM).
However, such solid-state memory systems tend to have long latency periods for processing data. Typically, commands and addresses can be transferred to the solid-state memory systems at rates on the order of nanoseconds, while data processing by the solid-state memory in response to the commands and addresses often takes a significantly longer time, as high as microseconds.
Traditional memory interfaces access one solid-state memory system at a time, pausing for a ready signal from the solid-state memory system. Even in memory interfaces that have access to multiple solid-state memory devices, operations on the memory devices are typically performed one at a time, with the interface pausing for completion of each operation before beginning another operation. For example, traditional memory interfaces may write one page to a first memory device and pause, waiting for the write operation to be completed, before writing a second page to a second memory device. In another example, traditional memory interfaces wait for a block erase command to complete on a first memory device before beginning a block erase command on a second memory device. In other traditional systems, operations on all devices must complete before a second set of operations may begin.
As such, data buses between a memory interface and a solid-state memory device, in addition to data buses between the memory interface and a direct memory access controller, may suffer from extended periods of inactivity during memory device data processing, resulting in a reduced effective use of the data buses. For data intensive activities and, in particular, for activities on devices, such as MP3 players and cameras, reduced effective data transfer rates through data buses result in reduced performance of the devices. As such, an improved system and method for transferring data to and from memory devices would be desirable.
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